Answer:
The "point" is the undefined term needed to define an angle.
Step-by-step explanation:
Geometry has three fundamental undefined elements: point, straight and flat. One point only has a position in space. It has no dimension (length, width, height). The line is a geometric figure that is generated by a moving point and is formed by the union of points. Finally, a plane is a completely flat surface that has length and width but not thickness. The plane has two dimensions and extends infinitely.
An angle is the portion of the plane between two semi-lines that have the common origin. It is formed by the side (each of the two half-lines) the vertex (point where the two half-lines coincide) and the amplitude (measure of the opening between the sides).
Taking into account what was previously said, you can say that <u><em>the "point" is the undefined term needed to define an angle. </em></u>The angle is determined by three points that call it A, B, C, with A ≠ C and B ≠ C, in which one of those points is the vertex. This is shown in the image.